Theoretical assessment of dilute acetone removal from aqueous streams by membrane distillation

The removal of dilute acetone from aqueous streams by air-gap membrane dist illation is theoretically assessed. A combined heat and mass transfer model that includes temperature and concentration polarization effects as well a s temperature and concentration variation along the module length is employ ed to predict the flux and selectivity of acetone under the relevant proces s operating conditions. Three mass transfer solutions are heeded in the mod el: the exact Stefan-Maxwell, the approximate Stefan-Maxwell, and the Ficki an binary solution. Although, behaviorally, the three solutions exhibit the same trends, quantitatively some differences exist between the Fickian-bas ed solution on the one hand and the Stefan-Maxwell solutions on the other h and. The exact and approximate solutions of the Stefan-Maxwell equation sho wed a similar capability in predicting the process achievement under all pr ocess conditions, Predictions showed that acetone selectivity and flux were strongly dependent on feed conditions and air-gap width.